So I just got taking the scanner to my Bonnie and it came up with this code..

P1133 H025 B1 S1 - Insufficient Switching

I have no clue what this is, maybe the O2 Sensor? Any ideas?

Your primary oxygen sensor most likely needs replaced. I just mean that the voltage isnt changing enough for the PCM to maintain a 14.7 afr

Agreed. The sensor is located in the rear exhaust manifold and should barely be visible is you look down between the engine and firewall of the car.

Hey, here is a good example of what that code means. Take a look at the graph for O2 B1S1 (Dark Blue), that'* the main oxygen sensor voltage. When you are cruising the PCM tries to keep the Air Fuel ratio as close to 14.7 as it can, by going slightly leaner and richer and then reading the changes in the sensor output. If the PCM doesn't see these small voltage changes is assumes the O2 sensor is bad and throws the Check Engine Light.

Thanks for feedback

DTC P1133

<A href="http://127.0.0.1:9001/servlets/BlobShtml?ShtmlFile=790607&evc=sm&pubid=263&cellId =25849&mspsdsubkey=2073#ss1-790607">Circuit Description

Heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content of the exhaust stream. When the vehicle is first started, the powertrain control module (PCM) operates in an Open Loop mode, ignoring the HO2S signal voltage when calculating the air-to-fuel ratio. The PCM supplies the HO2S with a reference or bias voltage of about 450 mV. The HO2S generates a voltage within a range of 0-1,000 mV that fluctuates above and below bias voltage once in Closed Loop. A high HO2S voltage output indicates a rich fuel mixture. A low HO2S voltage output indicates a lean mixture. Heating elements inside the HO2S minimize the time required for the sensors to reach operating temperature, and provide an accurate voltage signal. The PCM monitors the HO2S 1 rich-to-lean and lean-to-rich switching activity. This diagnostic trouble code (DTC) will set if the HO2S 1 voltage did not switch enough times during a calibrated time period.
Each HO2S has the following circuits:

• HO2S 1 high signal
• HO2S 1 low signal
• HO2S 1 heater ignition 1 voltage
• HO2S 1 heater ground

<A href="http://127.0.0.1:9001/servlets/BlobShtml?ShtmlFile=790607&evc=sm&pubid=263&cellId =25849&mspsdsubkey=2073#ss2-790607">Conditions for Running the DTC

• DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0125, P0128, P0201, P0202, P0203, P0204, P0205, P0206, P0410, P0440, P0442, P0443, P0446, P0449, or P1441 are not set.
• The PCM has commanded Closed Loop for at least 60 seconds.
• The engine speed is between 550-3,000 RPM.
• The engine coolant temperature (ECT) is more than 70°C (167°F).
• The mass air flow (MAF) is between 13-32 g/*.

<A href="http://127.0.0.1:9001/servlets/BlobShtml?ShtmlFile=790607&evc=sm&pubid=263&cellId =25849&mspsdsubkey=2073#ss3-790607">Conditions for Setting the DTC

The DTC will set if either of the following conditions are present for a 100 second monitoring period:

• The PCM has monitored fewer than 50 rich-to-lean switches.
• The PCM has monitored fewer than 55 lean to rich switches.

<A href="http://127.0.0.1:9001/servlets/BlobShtml?ShtmlFile=790607&evc=sm&pubid=263&cellId =25849&mspsdsubkey=2073#ss4-790607">Action Taken When the DTC Sets

• The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
• The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the operating conditions to the Freeze Frame and updates the Failure Records.

<A href="http://127.0.0.1:9001/servlets/BlobShtml?ShtmlFile=790607&evc=sm&pubid=263&cellId =25849&mspsdsubkey=2073#ss5-790607">Conditions for Clearing the DTC

• The PCM turns OFF the MIL after 3 consecutive ignition cycles that the diagnostic runs and passes.
• A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
• A DTC stored in history clears after 40 warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
• Use the scan tool in order to clear the DTC.

<A href="http://127.0.0.1:9001/servlets/BlobShtml?ShtmlFile=790607&evc=sm&pubid=263&cellId =25849&mspsdsubkey=2073#ss6-790607">Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. [*]

Step
Action
Values
Yes
No
Schematic Reference: Engine Controls Schematics
1
Did you perform the Diagnostic System Check-Engine Controls?
--
Go to Step 2
Go to Diagnostic System Check - Engine Controls
2

1. [*]

Does the HO2S 1 voltage fluctuate rapidly above and below the specified value?
350-550 mV
Go to Step 3
Go to Step 4
3

1. [*]

Does the DTC fail this ignition?
--
Go to Step 4
Go to Intermittent Conditions
4

1. [*]

Does the HO2S voltage read outside the specified range?
425-475 mV
Go to Step 7
Go to Step 5
5

1. [*]

Does the HO2S 1 voltage measure less than the specified amount?
25 mV
Go to Step 9
Go to Step 6
6

1. [*]

Do both resistance measurements equal less than the specified amount?
0-5 ohms
Go to Step 12
Go to Step 8
7
Test the affected HO2S high signal circuit short to ground or voltage. Refer to Circuit Testing in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 15
Go to Step 12
8
Repair the signal circuit that measured an open or high resistance. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?
--
Go to Step 15
--
9

1. [*]

Does the test lamp illuminate?
--
Go to Step 10
Go to DTC P0135
10
Before continuing inspect for the following conditions that may affect the HO2S operation:

• 
  Notice
  
  Contamination of the oxygen sensor can result from the use of an inappropriate RTV sealant (not oxygen sensor safe) or excessive engine coolant or oil consumption. Remove the HO2S and visually inspect the portion of the sensor exposed to the exhaust stream in order to check for contamination. If contaminated, the portion of the sensor exposed to the exhaust stream will have a white powdery coating. Silicon contamination causes a high but false HO2S signal voltage (rich exhaust indication). The control module will then reduce the amount of fuel delivered to the engine, causing a severe driveability problem. Eliminate the source of contamination before replacing the oxygen sensor.
  
  HO2S contamination--Inspect the HO2S for contamination.
• Notice
  
  Do not remove this pigtail from either the heated oxygen sensor (HO2S) or the oxygen sensor (O2S). Removing the pigtail or the connector will affect sensor operation.
  Handle the oxygen sensor carefully. Do not drop the HO2S. Keep the in-line electrical connector and the louvered end free of grease, dirt, or other contaminants. Do not use cleaning solvents of any type.
  Do not repair the wiring, connector or terminals. Replace the oxygen sensor if the pigtail wiring, connector, or terminal is damaged.
  This external clean air reference is obtained by way of the oxygen sensor signal and heater wires. Any attempt to repair the wires, connectors, or terminals could result in the obstruction of the air reference and degraded sensor performance.
  The following guidelines should be used when servicing the heated oxygen sensor:
  • Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance.
  • Do not damage the sensor pigtail and harness wires in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems.
  • Ensure the sensor or vehicle lead wires should not be bent sharply or kinked. Sharp bends or kinks could block the reference air path through the lead wire.
  • Do not remove or defeat the oxygen sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will cause poor engine performance.
  • Ensure that the peripheral seal remains intact on the vehicle harness connector in order to prevent damage due to water intrusion. The engine harness may be repaired using Packard'* Crimp and Splice Seals Terminal Repair Kit. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed.
  
  Chafed, burnt, cut, pinched, or otherwise damaged HO2S wiring
• The HO2S must have a clean air reference in order to function properly. This clean air reference is obtained by way of the HO2S wires. Obstruction of the air reference and degraded HO2S performance could result from any attempt to repair the above conditions.
• Exhaust system leaks or restrictions
• Evaporative emissions (EVAP) canister purge Inspect the EVAP control system. Refer to Inspection/Maintenance (I/M) Evaporative Emission (EVAP) System Set Procedure .
• The fuel pressure Incorrect fuel pressure can affect HO2S operation. Refer to Fuel System Diagnosis .

Did you find and correct the condition?
--
Go to Step 15
Go to Step 11
11
Before continuing, inspect for poor connections at the affected HO2S connector. Refer to Testing for Intermittent and Poor Connections in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 15
Go to Step 13
12
Inspect for poor connections at the PCM harness connectors. Refer to Testing for Intermittent and Poor Connections in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 15
Go to Step 14
13
Replace the affected HO2S. Refer to Heated Oxygen Sensor (HO2S) 1 Replacement or Heated Oxygen Sensor (HO2S) 2 Replacement .
Did you complete the replacement?
--
Go to Step 15
--
14
Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement .
Did you complete the replacement?
--
Go to Step 15
--
15

1. [*]

Does the DTC run and pass?
--
Go to Step 16
Go to Step 2
16
With a scan tool, observe the stored information, Capture Info.
Does the scan tool display any DTCs that you have not diagnosed?
--
Go to Diagnostic Trouble Code (DTC) List
System OK

Document ID# 790607
2002 Pontiac Bonneville

I have a 98 *-10 4 cyl auto. It continues to throw the 1133 code. I had a mechanic work on it quite a bit ($300+ worth) and it cleared up for a while, enough for me to pass inspection and then some. All of a sudden it has started again. It has a new H20S. The mechanic sez he found a number of bad grounds and some pinched/broken wires. Here'* my question: could I temporarily replace the wire from the H2OS to the computer to see if that is the problem? If so, how do I find the correct input to the PCM?

Thanks -- And by the way, thanks loads to Tom Sawyer Man for the detailed procedures.

Please refrain from posting in old threads. Instead, start a new one with a link directed to this one.

Thread closed.